88 Report of the President 



and native horse, characteristic prehistoric animals of the Mid- 

 dle West. Preliminary studies have been made and approved 

 for the remaining murals in this hall. 



A skeleton of the great long- jawed mastodon Megabelodon 



has been purchased from the discoverer, Captain E. L. Troxell, 



and will be restored and mounted in the series 



Skdeton MaSt ° d0n of fossil Proboscideans - The Megabelodon 



was an animal equaling the great American 



Mastodon in bulk but having shorter legs and greatly elongated 



jaws. It inhabited North America during the Pliocene epoch. 



A number of important specimens of the very primitive 



mammals of the oldest Tertiary formations have been prepared, 



especially the skeletons of Ectoconus and 



The Oldest Pantolambda, skull of Triisodon and remains 



Tertiary Mammals . ... 



of various new or rare species of minute size. 

 These specimens are of great scientific interest as they throw 

 much light upon the origin and early evolution of the mammals. 



The postponement of field expeditions has notably increased 

 the amount of research work in the department. An important 

 book published by Professor Osborn, "The 

 Origin and Evolution of Life on Earth," dis- 

 cusses the broader evolutionary problems in the light of recent 

 researches, especially in biochemistry and allied subjects, pre- 

 senting new or little considered aspects of evolutionary theory. 

 Professor Osborn has in press a revision of the later Tertiary 

 fossil horses marking the completion of an important stage in 

 his studies on the Evolution of the Horse. He has likewise 

 continued his monographic revision of the sauropodous dino- 

 saurs, assisted by Dr. Mook, and has the monograph upon the 

 Titanotheriidse nearly ready for the press. Dr. Matthew and 

 Mr. Granger have continued or completed various studies upon 

 fossil mammals, Mr. Brown upon dinosaurs, and Dr. Gregory 

 upon the primates (monkeys and lemurs) and upon the very 

 ancient reptiles of the Permian period. Some results of these 

 various researches are contained in eight articles in the Mu- 

 seum Bulletin; the greater part are not yet in shape for pub- 

 lication. 



